P0088

CIRCUIT DESCRIPTION
The engine control module (ECM) monitors fuel rail pressure (FRP) using the FRP sensor. If the sensor indicates a pressure more than the commanded rail pressure plus a possible transitional overshoot, The ECM will set diagnostic trouble code (DTC) P0088 for fuel rail pressure too high.

CONDITIONS FOR RUNNING THE DTC
^ DTCs P0192, P0193, or P1635 are not set.
^ The ignition is ON.

CONDITIONS FOR SETTING THE DTC
The actual fuel pressure is more than 167 MPa.

ACTION TAKEN WHEN THE DTC SETS
^ The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
^ The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.
^ The control module will limit fuel injection and fuel rail pressure.

CONDITIONS FOR CLEARING MIL/DTC
^ The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
^ A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
^ A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
^ Clear the MIL and the DTC with a scan tool.

DIAGNOSTIC AIDS
If the fuel system pressure is actually too high, a fuel knock and smoke condition will exist.

The most likely cause of this DTC is a sticking fuel rail pressure regulator.

TEST DESCRIPTION

DTC P0088 - Steps 1-4:

DTC P0088 - Steps 5-12:

The numbers below refer to the step numbers on the diagnostic table.
3. DTC P0090 is a current flow problem in the FRP regulator circuit. This incorrect current draw could lead to incorrect fuel pressure. This hardware problem should be diagnosed before the performance DTC is checked.